The present invention relates to an ink jet recording method and an apparatus for that method, wherein image information is sensed by an image acquiring apparatus, and its energy is converted into image signals which are used for recording through ink-jetting.
There has so far been employed a method wherein electromagnetic waves (visible light, X-rays etc.) arriving from an object are sensed by silver halide light-sensitive materials which are then subjected to prescribed processing, and images are recorded on the silver halide light-sensitive material itself or on another silver halide light-sensitive material.
In recent years, the electromagnetic waves (visible light, X-rays etc.) arriving from an object are made temporarily to be image signals showing images by an image acquiring apparatus (for example, an electronic camera, or an apparatus which takes out radiographic image information as electric signals), and the image signals thus obtained are used to record images.
As a method to record images by using the obtained image signals, there is given a recording method to record images by using a recording medium represented by a silver halide light-sensitive material or an ink jet recording method to record by jetting ink.
As stated above, it has been conducted in recent years that energy of electromagnetic waves arriving from an object is acquired temporarily by an image acquiring apparatus as image signals showing images, and images are recorded by an ink jet recording apparatus based on the acquired image signals.
Compared with a silver halide light-sensitive material recording system, this ink jet recording system has an advantage that a recording means which is not restricted in terms of installation position and is extremely easy to operate can be provided because it has no steps for developing and fixing, and it requires neither facilities of water supply and water draining nor replenishment of developing solution to be free from an offensive odor.
On the other side, however, the ink jet system has been inferior to the silver halide light-sensitive material system on the point of image quality. A ground for the foregoing is that the characteristic curve for obtaining images with high image quality needs to be solved in the ink jet recording, in particular, although the characteristic curve for smooth image density change can easily be obtained.
Characteristics for recording in a conventional ink jet recording apparatus are shown in FIG. 49. The axis of abscissas represents image signal S to be inputted in an ink jet printer, while, the axis of ordinates represents optical density D recorded on a recording medium, and optical density D is reproduced in the linear relationship between image signal S and optical density D. On the other hand, in the example of a radiographic image acquiring apparatus employing stimulable phosphor which is an example of an acquiring apparatus, the relationship between a logarithmic value of energy of X-rays representing electromagnetic waves transmitted through an object and image signal S to be obtained proves to be one shown in FIG. 50. Therefore, the characteristics in the case of recording images by using both of them prove to be one shown in FIG. 51. It has been impossible, in the conventional ink jet recording, to obtain sufficient image quality in terms of image smoothness, graininess and sharpness.
It was further impossible to obtain image quality that is fit for diagnoses, when recording medical images, especially when recording monochromatic medical images, by using an ink jet recording apparatus.
The reason for the foregoing is as follows. Monochromatic medical images are usually recorded on a transparent or translucent medium, to be observed as a transmission image. In the case of a transmission image, it is difficult to realize high density because its optical density is observed to be low even when the same quantity of ink as on a reflection image is stuck on the transmission image, and moreover, image unevenness and graininess on the transmission image tend to be noticeable, compared with a reflection image. Since a hard copy of medical images is required to have delicate density gradation expression, graininess and density uniformity, even when the transmission image is more disadvantageous than the reflection image as stated above, it is extremely difficult to provide a hard copy that is fit for diagnoses.
The present invention has been achieved in view of the technical problems stated above, and its object is to provide a recording method and an apparatus for that recording method both for high image quality, in ink jet recording, and in particular, to provide an ink jet recording method and an apparatus for that recording method which can obtain monochromatic and medical image hard copies which are fit for diagnoses.
The problems mentioned above can be solved by the following structures indicated with number enclosed in parentheses.
(1-1) An ink-jet recording apparatus, comprises:
an acquiring device to input an image signal obtained by converting energy of electromagnetic waves transmitting through a subject or energy of electromagnetic waves reflected from a subject for each predetermined region;
an ink head to jet ink stored therein; and
a controller to control the ink head so as to jet ink based on the image signal acquired by the acquiring device onto a recording medium on which an image is recorded,
wherein when an intensity of the energy of electromagnetic waves of a predetermined region is E and an optical density of the image recorded on the recording medium based on the image signal is D, the controller conducts the image recording such that a characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E becomes a monotone increasing function or a monotone decreasing function,
wherein, energy intensities E1 to E6 are selected to be E1 less than E2 less than E3 less than E4 less than E5 less than E6 and each energy intensity Ei is defined to be an energy intensity corresponding to an optical density Di represented the following formula,
Di=kixc2x7Dmax+(1xe2x88x92ki)xc2x7Dmin,
where i is an integer of 1 to 6, when the characteristic curve is the monotone increasing function, k1=0.1, k2=0.2, k3=0.3, k4=0.6, k5=0.8, and k6=0.9, and when the characteristic curve is the monotone decreasing function, k1=0.9, k2=0.8, k3=0.6, k4=0.3, k5=0.2, and k6=0.1,
wherein when xcex31, xcex32 and xcex33 are defined on the characteristic curve such that an inclination of a line connecting points corresponding to E1 and E2 is xcex31, an inclination of a line connecting points corresponding to E3 and E4 is xcex32, and an inclination of a line connecting points corresponding to E5 and E6 is xcex33, the characteristic curve is determined so as to satisfy the following formulas:
|xcex31| less than |xcex32| and |xcex33| less than |xcex32|, and
wherein the image recording for the energy intensity E between E1 and E2 is conducted based on xcex31, the image recording for the energy intensity E between E3 and E4 is conducted based on xcex32, and the image recording for the energy intensity E between E5 and E6 is conducted based on xcex33.
(1-2) In the ink-jet recording apparatus of (1-1), the controller conducts the image recording such that the characteristic curve representing the change of the optical density D for the logarithm of the energy intensity E becomes the simple increasing function.
(1-3) In the ink-jet recording apparatus of (1-1), the controller conducts the image recording such that the characteristic curve representing the change of the optical density D for the logarithm of the energy intensity E becomes the simple decreasing function.
(1-4) In the ink-jet recording apparatus of (1-1), the characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E is the monotone decreasing function, the controller comprises a converter to convert an image signal S into an image signal Sxe2x80x2 and the converter makes a converting curve representing a change of the after-conversion image signal Sxe2x80x2 for the image signal S to be a monotone increasing function, wherein image signals S1 to S6 are selected to be S1 less than S2 less than S3 less than S4 less than S5 less than S6, and when xcex11, xcex12 and xcex13 are defined on the characteristic curve such that an inclination of a line connecting points corresponding to S1 and S2 is xcex11, an inclination of a line connecting points corresponding to S3 and S4 is xcex12, and an inclination of a line connecting points corresponding to S5 and S6 is xcex13, the characteristic curve is determined so as to satisfy the following formulas:
|xcex11| less than xcex12| and |xcex13| less than xcex12|, and
wherein the image conversion for the image signal S between S1 and S2 is conducted based on xcex11, the image conversion for the image signal S between S3 and S4 is conducted based on xcex12, and the image conversion for the image signal S between S5 and S6 is conducted based on xcex13.
(1-5) In the ink-jet recording apparatus of (1-1), the characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E is the monotone decreasing function, the controller comprises a converter to convert an image signal S into an image signal Sxe2x80x2 and the converter makes a converting curve representing a change of the after-conversion image signal Sxe2x80x2 for the image signal S to be a monotone decreasing function, and
wherein image signals S1 to S6 are selected to be S1 less than S2 less than S3 less than S4 less than S5 less than S6, and when xcex11, xcex12 and xcex13 are defined on the characteristic curve such that an inclination of a line connecting points corresponding to S1 and S2 is xcex11, an inclination of a line connecting points corresponding to S3 and S4 is xcex12, and an inclination of a line connecting points corresponding to S5 and S6 is xcex13, the characteristic curve is determined so as to satisfy the following formulas:
|xcex11| less than xcex12| and |xcex13| less than xcex12|, and
wherein the image conversion for the image signal S between S1 and S2 is conducted based on xcex11, the image conversion for the image signal S between S3 and S4 is conducted based on xcex12, and the image conversion for the image signal S between S5 and S6 is conducted based on xcex13.
(1-6) In the ink-jet recording apparatus of (1-2), the image recording is conducted with the number of density gradation steps of 16 or more in a range of D1xe2x89xa6Dxe2x89xa6D2.
(1-7) In the ink-jet recording apparatus of (1-2), the image recording is conducted with the number of density gradation steps of 32 or more in a range of D3xe2x89xa6Dxe2x89xa6D4.
(1-8) In the ink-jet recording apparatus of (1-1), the characteristic curve comprises a portion convex downward.
(1-9) In the ink-jet recording apparatus of (1-1), the characteristic curve comprises a portion convex upward.
(1-10) In the ink-jet recording apparatus of (1-1), the characteristic curve comprises a portion convex upward and another portion convex downward.
(1-11) In the ink-jet recording apparatus of (1-1), the characteristic curve comprises a point of inflection.
(1-12) In the ink-jet recording apparatus of (1-1), the electromagnetic waves are X-rays transmitting through the subject.
(1-13) In the ink-jet recording apparatus of (1-12), the image signals have a linear relationship with the intensity of the energy of X-rays.
(1-14) In the ink-jet recording apparatus of (1-12), the image signals have a linear relationship with the logarithm of the intensity of the energy of X-rays.
(1-15) In the ink-jet recording apparatus of (1-1), the range of D3 less than D less than D4 is a range within which an image of the subject exists.
(1-16) In the ink-jet recording apparatus of (1-1), the range of D5 less than D less than D6 is a range within which an image of the subject does not exist.
(1-17) In the ink-jet recording apparatus of (1-3), the image recording is conducted with the number of density gradation steps of 16 or more in a range of D1xe2x89xa6Dxe2x89xa6D2.
(1-18) In the ink-jet recording apparatus of (1-3), the image recording is conducted with the number of density gradation steps of 32 or more in a range of D3xe2x89xa6Dxe2x89xa6D4.
(1-19) In the ink-jet recording apparatus of (1-2), the characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E is the monotone increasing function, and when the energy intensity E is within a range of E1 less than E less than E2, the image recording is conducted with ink other than ink having a maximum density.
(1-20) In the ink-jet recording apparatus of (1-19), when the energy intensity E is within a range of E5 less than E less than E6, the image recording is conducted by using ink having a maximum density with an amount of 50% or more of the total amount of ink used for the image recording.
(1-21) In the ink-jet recording apparatus of (1-19), when the energy intensity E is within a range of E1 less than E less than E2, the image recording is conducted by using ink having a minimum density with an amount of 50% or more of the total amount of ink used for the image recording.
(1-22) In the ink-jet recording apparatus of (1-3), the characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E is the monotone decreasing function, and when the energy intensity E is within a range of E5 less than E less than E6, the image recording is conducted with ink other than ink having a maximum density.
(1-23) In the ink-jet recording apparatus of (1-22), when the energy intensity E is within a range of E1 less than E less than E2, the image recording is conducted by using ink having a maximum density with an amount of 50% or more of the total amount of ink used for the image recording.
(1-24) In the ink-jet recording apparatus of (1-22), when the energy intensity E is within a range of E5 less than E less than E6, the image recording is conducted by using ink having a minimum density with an amount of 50% or more of the total amount of ink used for the image recording.
(1-25) An ink-jet recording method, comprises:
forming an image by jetting ink onto a recording medium based on image signals obtained by converting by converting energy of electromagnetic waves transmitting through a subject or energy of electromagnetic waves reflected from a subject for each predetermined region;
wherein when an intensity of the energy of electromagnetic waves of a predetermined region is E and an optical density of the image recorded on the recording medium based on the image signal is D, the image recording is conducted such that a characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E becomes a monotone increasing function or a monotone decreasing function,
wherein, energy intensities E1 to E6 are selected to be E1 less than E2 less than E3 less than E4 less than E5 less than E6 and each energy intensity Ei is defined to be an energy intensity corresponding to an optical density Di represented the following formula,
Di=kixc2x7Dmax+(1xe2x88x92ki)xc2x7Dmin,
where i is an integer of 1 to 6, when the characteristic curve is the monotone increasing function, k1=0.1, k2=0.2, k3=0.3, k4=0.6, k5=0.8, and k6=0.9, and when the characteristic curve is the monotone decreasing function, k1=0.9, k2=0.8, k3=0.6, k4=0.3, k5=0.2, and k6=0.1,
wherein when xcex31, xcex32 and xcex33 are defined on the characteristic curve such that an inclination of a line connecting points corresponding to E1 and E2 is xcex31, an inclination of a line connecting points corresponding to E3 and E4 is xcex32, and an inclination of a line connecting points corresponding to E5 and E6 is xcex33, the characteristic curve is determined so as to satisfy the following formulas:
|xcex31| less than |xcex32| and |xcex33| less than |xcex32|, and
wherein the image recording for the energy intensity E between E1 and E2 is conducted based on xcex31, the image recording for the energy intensity E between E3 and E4 is conducted based on xcex32, and the image recording for the energy intensity E between E5 and E6 is conducted based on xcex33.
(1-26) In the ink-jet recording method of (1-25), the characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E is the monotone increasing function, and when the energy intensity E is within a range of E1 less than E less than E2, the image recording is conducted with ink other than ink having a maximum density.
(1-27) In the ink-jet recording method of (1-25), the characteristic curve representing a change of the optical density D for a logarithm of the energy intensity E is the monotone decreasing function, and when the energy intensity E is within a range of E5 less than E less than E6, the image recording is conducted with ink other than ink having a maximum density.
Further, the problems mentioned above may be solved by the following preferable structures.
(Structure 1) An ink jet recording method to form an image on a recording medium by jetting ink based on image signals obtained by converting energy of electromagnetic waves transmitted through an object and/or electromagnetic waves reflected on an object for each prescribed area, wherein recording is conducted so that a characteristic curve representing a change of optical density D of an image for a logarithmic value of the energy intensity E may be a monotone increasing function when assuming that energy intensity of electromagnetic waves in a given prescribed area is represented by E, and optical density of an image formed on a recording medium based on the energy intensity E is represented by D, while, recording is conducted with xcex31 when the energy intensity E is in a range of E1 less than E less than E2, recording is conducted with xcex32 when the energy intensity E is in a range of E3 less than E less than E4 and recording is conducted with xcex33 when the energy intensity E is in a range of E5 less than E less than E6.
However, E1 less than E2 less than E3 less than E4 less than E5 less than E6 holds, and each energy intensity Ei is energy intensity corresponding to optical density Di of the following each image. (i is an integer representing each of 1-6)
Di=kiDmax+(1xe2x88x92ki)Dmin
(k1=0.1, k2=0.2, k3=0.3, k4=0.6, k5=0.8, k6=0.9)
An inclination of a straight line connecting two points on the characteristic curve at E1 and E2 is represented by xcex31, an inclination of a straight line connecting two points on the characteristic curve at E3 and E4 is represented by xcex32and an inclination of a straight line connecting two points on the characteristic curve at E5 and E6 is represented by xcex33, and |xcex31| less than |xcex32| and |xcex33| less than |xcex32| hold.
(Structure 2) An ink jet recording method to form an image on a recording medium by jetting ink based on image signals obtained by converting energy of electromagnetic waves transmitted through an object and/or electromagnetic waves reflected on an object for each prescribed area, wherein recording is conducted so that a characteristic curve representing a change of optical density D of an image for a logarithmic value of the energy intensity E may be a monotone decreasing function when assuming that energy intensity of electromagnetic waves in a given prescribed area is represented by E, and optical density of an image formed on a recording medium based on the energy intensity E is represented by D, while, recording is conducted with xcex31, when the energy intensity E is in a range of E1 less than E less than E2, recording is conducted with xcex32 when the energy intensity E is in a range of E3 less than E less than E4 and recording is conducted with xcex33 when the energy intensity E is in a range of E5 less than E less than E6.
However, E1 less than E2 less than E3 less than E4 less than E5 less than E6 holds, and each energy intensity Ei is energy intensity corresponding to optical density Di of the following each image. (i is an integer representing each of 1-6)
Di=kiDmax+(1xe2x88x92ki)Dmin
(k1=0.9, k2=0.8, k3=0.6, k4=0.3, k5=0.2, k6=0.1)
An inclination of a straight line connecting two points on the characteristic curve at E1 and E2 is represented by xcex31, an inclination of a straight line connecting two points on the characteristic curve at E3 and E4 is represented by xcex32 and an inclination of a straight line connecting two points on the characteristic curve at E5 and E6 is represented by xcex33, and |xcex31| less than |xcex32| and |xcex33| less than |xcex32| hold following structures.
(Structure 3) The ink jet recording method according to either one of the Structures 1 and 2, wherein the characteristic curve is one having therein a portion convex downward.
(Structure 4) The ink jet recording method according to either one of the Structures 1 and 2, wherein the characteristic curve is one having therein a portion convex upward.
(Structure 5) The ink jet recording method according to either one of the Structures 1-4, wherein the characteristic curve is one having therein a portion convex downward and a portion convex upward.
(Structure 6) The ink jet recording method according to either one of the Structures 1-5, wherein the characteristic curve has a point of inflection.
(Structure 7) The ink jet recording method according to either one of the Structures 1-6, wherein the electromagnetic waves are X-rays obtained through transmission through an object.
(Structure 8) The ink jet recording method according to Structures 7, wherein the image signals have linear relationship with the X-ray energy intensity.
(Structure 9) The ink jet recording method according to Structures 7, wherein the image signals have linear relationship with a logarithmic value of the X-ray energy intensity.
(Structure 10) The ink jet recording method according to either one of the Structures 7-9, wherein the range of D3 less than D less than D4 is a range of an object image.
(Structure 11) The ink jet recording method according to either one of the Structures 7-9, wherein the range of D5 less than D less than D6 is a range where no object image is present.
(Structure 12) The ink jet recording method according to either one of the Structures 1-11, wherein the recording medium is transparent or translucent.
(Structure 13) The ink jet recording method according to either one of the Structures 1-12, wherein the recording medium is one of a void type.
(Structure 14) The ink jet recording method according to either one of the Structures 7-9, wherein image recording is changed based on information showing whether the image signal is in linear relationship with an X-ray quantity or is in linear relationship with a logarithmic value of an X-ray quantity.
(Structure 2-15) The ink jet recording method according to either one of the Structures 1-14, wherein the image signal obtained is subjected to different image processing in accordance with a difference of recording characteristics of an ink jet recording apparatus.
(Structure 16) The ink jet recording method according to either one of the Structures 1-15, wherein recording is conducted with recording density gradation number of 16 or more in a range of D1xe2x89xa6Dxe2x89xa6D2.
(Structure 17) The ink jet recording method according to either one of the Structures 1-16, wherein recording is conducted with recording density gradation number of 32 or more in a range of D3 less than D less than D4.
(Structure 18) An ink jet recording apparatus to form an image on a recording medium by jetting ink based on image signals obtained by converting energy of electromagnetic waves transmitted through an object and/or electromagnetic waves reflected on an object for each prescribed area, wherein recording is conducted so that a characteristic curve representing a change of optical density D of an image for a logarithmic value of the energy intensity E may be a monotone increasing function when assuming that energy intensity of electromagnetic waves in a given prescribed area is represented by E, and optical density of an image formed on a recording medium based on the energy intensity E is represented by D, while, recording is conducted with xcex31 when the energy intensity E is in a range of E1 less than E less than E2, recording is conducted with xcex32 when the energy intensity E is in a range of E3 less than E less than E4 and recording is conducted with xcex33 when the energy intensity E is in a range of E5 less than E less than E6.
However, E1 less than E2 less than E3 less than E4 less than E5 less than E6 holds, and each energy intensity Ei is energy intensity corresponding to optical density Di of the following each image. (i is an integer representing each of 1-6)
xe2x80x83Di=kiDmax+(1xe2x88x92ki)Dmin
(k1=0.1, k2=0.2, k3=0.3, k4=0.6, k5=0.8, k6=0.9)
An inclination of a straight line connecting two points on the characteristic curve at E1 and E2 is represented by xcex31, an inclination of a straight line connecting two points on the characteristic curve at E3 and E4 is represented by xcex32 and an inclination of a straight line connecting two points on the characteristic curve at E5 and E6 is represented by xcex33, and |xcex31| less than |xcex32| and |xcex33| less than |xcex32| hold.
(Structure 19) The ink jet recording apparatus according to Structure 18, wherein a conversion means which converts the image signal S into image signal Sxe2x80x2 is provided, and the conversion means makes a conversion curve showing a change of the image signal Sxe2x80x2 after conversion from the image signal S to be a monotone increasing function, and an inclination of the conversion curve is made by the conversion means to be al when the image signal S is in a range of S1 less than S less than S2, an inclination of the conversion curve is made by the conversion means to be xcex12 when the image signal S is in a range of S3 less than S less than S4, and an inclination of the conversion curve is made by the conversion means to be xcex13 when the image signal S is in a range of S5 less than S less than S6.
However, S1 less than S2 less than S3 less than S4 less than S5 less than S6 holds, and an inclination of a straight line connecting two points at S1and S2 on the conversion curve is represented by xcex11, an inclination of a straight line connecting two points at S3 and S4 on the conversion curve is represented by xcex12, and an inclination of a straight line connecting two points at S5 and S6 on the conversion curve is represented by xcex13, and |xcex11| less than |xcex12| and |xcex13| less than |xcex12| hold.
(Structure 20) An ink jet recording apparatus to form an image on a recording medium by jetting ink based on image signals obtained by converting energy of electromagnetic waves transmitted through an object and/or electromagnetic waves reflected on an object for each prescribed area, wherein recording is conducted so that a characteristic curve representing a change of optical density D of an image for a logarithmic value of the energy intensity E may be a monotone decreasing function when assuming that energy intensity of electromagnetic waves in a given prescribed area is represented by E, and optical density of an image formed on a recording medium based on the energy intensity E is represented by D, while, recording is conducted with xcex31 when the energy intensity E is in a range of E1 less than E less than E2, recording is conducted with xcex32 when the energy intensity E is in a range of E3 less than E less than E4 and recording is conducted with xcex33 when the energy intensity E is in a range of E5 less than E less than E6.
However, E1 less than E2 less than E3 less than E4 less than E5 less than E6 holds, and each energy intensity Ei is energy intensity corresponding to optical density Di of the following each image. (i is an integer representing each of 1-6)
Di=kiDmax+(1xe2x88x92ki)Dmin
(k1=0.9, k2=0.8, k3=0.6, k4=0.3, k5=0.2, k6=0.1)
An inclination of a straight line connecting two points on the characteristic curve at E1 and E2 is represented by xcex11, an inclination of a straight line connecting two points on the characteristic curve at E3 and E4 is represented by xcex32 and an inclination of a straight line connecting two points on the characteristic curve at E5 and E6 is represented by xcex33, and |xcex31| less than |xcex32| and |xcex33| less than |xcex32| hold.
(Structure 21) The ink jet recording apparatus according to Structure 21, wherein a conversion means which converts the image signal S into image signal Sxe2x80x2 is provided, and the conversion means makes a conversion curve showing a change of the image signal Sxe2x80x2 after conversion from the image signal S to be a monotone decreasing function, and an inclination of the conversion curve is made by the conversion means to be xcex11 when the image signal S is in a range of S1 less than S less than S2, an inclination of the conversion curve is made by the conversion means to be xcex12 when the image signal S is in a range of S3 less than S less than S4, and an inclination of the conversion curve is made by the conversion means to be xcex13 when the image signal S is in a range of S5 less than S less than S6.
However, S1 less than S2 less than S3 less than S4 less than S5 less than S6 holds, and an inclination of a straight line connecting two points at S1 and S2 on the conversion curve is represented by xcex11, an inclination of a straight line connecting two points at S3 and S4 on the conversion curve is represented by xcex12, and an inclination of a straight line connecting two points at S5 and S6 on the conversion curve is represented by xcex13, and |xcex11| less than |xcex12| and |xcex13| less than |xcex12| hold.
(Structure 22) The ink jet recording apparatus according to either one of the Structures 18-21, wherein recording is conducted with recording density gradation number of 16 or more in a range of D1xe2x89xa6Dxe2x89xa6D2.
(Structure 23) The ink jet recording apparatus according to either one of the Structures 18-22, wherein recording is conducted with recording density gradation number of 32 or more in a range of D3xe2x89xa6Dxe2x89xa6D4.
(Structure 24) An ink jet recording method to form an image on a recording medium by jetting ink based on image signals obtained by converting energy of electromagnetic waves transmitted through an object and/or electromagnetic waves reflected on an object for each prescribed area, wherein aforesaid ink represents plural ink groups each having different optical density, and recording is conducted so that a characteristic curve representing a change of optical density D of an image for a logarithmic value of the energy intensity E may be a monotone increasing function when assuming that energy intensity of electromagnetic waves in a given prescribed area is represented by E, and optical density of an image formed on a recording medium based on the energy intensity E is represented by D, while, recording is conducted with xcex31 by the use of ink other than the highest density ink when the energy intensity E is in a range of E1 less than E less than E2, recording is conducted with xcex32 when the energy intensity E is in a range of E3 less than E less than E4 and recording is conducted with xcex33 when the energy intensity E is in a range of E5 less than E less than E6.
However, E1 less than E2 less than E3 less than E4 less than E5 less than E6 holds, and each energy intensity Ei is energy intensity corresponding to optical density Di of the following each image. (i is an integer representing each of 1-6)
Di=kiDmax+(1xe2x88x92ki)Dmin
(k1=0.1, k2=0.2, k3=0.3, k4=0.6, k5=0.8, k6=0.9)
An inclination of a straight line connecting two points on the characteristic curve at E1 and E2 is represented by an inclination of a straight line connecting two points on the characteristic curve at E3 and E4 is represented by xcex32 and an inclination of a straight line connecting two points on the characteristic curve at E5 and E6 is represented by xcex33, and |xcex31| less than |xcex32| and |xcex33| less than |xcex32| hold.
(Structure 25) The ink jet recording method according to Structure 24, wherein recording is conducted by using the highest density ink in quantity of 50% or more of the total quantity of ink used when the energy intensity E is in a range of E5 less than E less than E6.
(Structure 26) The ink jet recording method according to Structure 25, wherein recording is conducted by using the lowest density ink in quantity of 50% or more of the total quantity of ink used when the energy intensity E is in a range of E1 less than E less than E2.
(Structure 27) An ink jet recording method to form an image on a recording medium by jetting ink based on image signals obtained by converting energy of electromagnetic waves transmitted through an object and/or electromagnetic waves reflected on an object for each prescribed area, wherein aforesaid ink represents plural ink groups each having different optical density, and recording is conducted so that a characteristic curve representing a change of optical density D of an image for a logarithmic value of the energy intensity E may be a monotone decreasing function when assuming that energy intensity of electromagnetic waves in a given prescribed area is represented by E, and optical density of an image formed on a recording medium based on the energy intensity E is represented by D, while, recording is conducted with xcex31 when the energy intensity E is in a range of E1 less than E less than E2, recording is conducted with xcex32 when the energy intensity E is in a range of E3 less than E less than E4 and recording is conducted with xcex33 and by using the highest density ink when the energy intensity E is in a range of E5 less than E less than E6.
However, E1 less than E2 less than E3 less than E4 less than E5 less than E6 holds, and each energy intensity Ei is energy intensity corresponding to optical density Di of the following each image. (i is an integer representing each of 1-6)
xe2x80x83Di=kiDmax+(1xe2x88x92ki)Dmin
(k1=0.9, k2=0.8, k3=0.6, k4=0.3, k5=0.2, k6=0.1)
An inclination of a straight line connecting two points on the characteristic curve at E1 and E2 is represented by xcex31, an inclination of a straight line connecting two points on the characteristic curve at E3 and E4 is represented by xcex32 and an inclination of a straight line connecting two points on the characteristic curve at E5 and E6 is represented by xcex33, and |xcex31| less than |xcex32| and |xcex33| less than |xcex32| hold.
(Structure 28) The ink jet recording method according to Structure 27, wherein recording is conducted by using the highest density ink in quantity of 50% or more of the total quantity of ink used when the energy intensity E is in a range of E1 less than E less than E2.
(Structure 29) The ink jet recording method according to Structure 28, wherein recording is conducted by using the lowest density ink in quantity of 50% or more of the total quantity of ink used when the energy intensity E is in a range of E5 less than E less than E6.
(Structure 30) The ink jet recording method according to either one of Structures 24-29, wherein aforesaid ink represents black ink having different optical density.
(Structure 31) The ink jet recording method according to either one of Structures 24-30, wherein optical density of aforesaid ink satisfies the following relational expression;
dnxe2x88x92dnxe2x88x921 greater than dnxe2x88x921 greater than dnxe2x88x922xe2x89xa7 . . . xe2x89xa7d2xe2x88x92d1 (n represents integers of 4 and over)
wherein, dn is optical density of each ink under the condition of dn less than dn+1.
(Structure 32) The ink jet recording method according to Structure 31, wherein optical density of aforesaid ink satisfies the following relational expression.
dnxe2x88x92dnxe2x88x921 greater than dnxe2x88x921 greater than dnxe2x88x922xe2x89xa7 . . . xe2x89xa7d2xe2x88x92d1xe2x89xa7d1 (n represents integers of 4 and over)
(Structure 33) The ink jet recording method according to either one of Structures 24-32, wherein aforesaid ink represents four types of ink each having different optical density, and d4xe2x88x92d3 greater than d3xe2x88x92d2xe2x89xa7d2d1xe2x89xa7d1 is satisfied when each optical density of ink represents each of d1, d2, d3 and d4 (d1 less than d2 less than d3 less than d4).
(Structure 34) The ink jet recording method according to either one of Structures 24-30, wherein aforesaid ink represents three types of ink each having different optical density, and d3xe2x88x92d2 greater than d2xe2x88x92d1xe2x89xa7d1 is satisfied when each optical density of ink represents each of d1, d2 and d3 (d1 less than d2 less than d3).
(Structure 35) The ink jet recording method according to either one of Structures 24-34, wherein optical density of aforesaid ink satisfies the following relational expression;
dn=dnxe2x88x921xc2x7r(r less than 1)
wherein, dn is optical density of each ink under the condition of dn less than dn+1.
(Structure 36) The ink jet recording method according to Structures 35, wherein the expression of r=xc2xd holds.
(Structure 37) The ink jet recording method according to either one of the Structures 24-36, wherein recording is conducted with recording density gradation number of 16 or more in a range of D1xe2x89xa6Dxe2x89xa6D2.
(Structure 38) The ink jet recording method according to either one of the Structures 24-36, wherein recording is conducted with recording density gradation number of 32 or more in a range of D3xe2x89xa6Dxe2x89xa6D4.
(Structure 39) An ink jet recording method to record on a recording medium by jetting ink, wherein four or more types of ink each having different optical density are used to express recording density gradation number N ranging from 256 to 16384.
(Structure 39xe2x80x2) The ink jet recording method according to Structures 39, wherein N is 1024 or more.
(Structure 39xe2x80x3) The ink jet recording method according to Structures 39xe2x80x2, wherein N is 4096 or more.
(Structure 40) An ink jet recording apparatus to record on a recording medium by jetting ink, wherein n-types of ink each having different optical density are used, and when N represents the recording density gradation number, N is equal to and greater than 81, and n is in a range from fourth power root of N to (fourth power root of N)xc3x973. (provided, however, that N is 81 or more)
(Structure 41) An ink jet recording method to record on a recording medium by jetting ink, wherein n-types of ink each having different optical density are used, and when N represents the recording density gradation number, N is equal to and greater than 81, and minimum recording density a is in a range from ((square root of N)/n)xc3x9780 dpi to ((square root of N)/n)xc3x97640 dpi.
(Structure 42) The ink jet recording method according to either one of Structures 39-40, wherein when n represents the number of types of optical density of ink used and N represents the recording density gradation number to be expressed, minimum recording density a is in a range from ((square root of N)/n)xc3x9780 dpi to ((square root of N)/n)xc3x97640 dpi.
(Structure 43) The ink jet recording method according to either one of Structures 39-42, wherein optical density of aforesaid ink satisfies the following relational expression;
dnxe2x88x92dnxe2x88x921 greater than dnxe2x88x921 greater than dnxe2x88x922xe2x89xa7 . . . xe2x89xa7d2xe2x88x92d1 (n represents integers of 4 and over)
wherein, dn is optical density of each ink under the condition of dn less than dn+1.
(Structure 44) The ink jet recording method according to Structure 43, wherein optical density of aforesaid ink satisfies the following relational expression.
dnxe2x88x92dnxe2x88x921 greater than dnxe2x88x921 greater than dnxe2x88x922xe2x89xa7 . . . xe2x89xa7d2xe2x88x92d1 (n represents integers of 4 and over)
(Structure 45) The ink jet recording method according to either one of Structures 39-44, wherein aforesaid ink represents four types of ink each having different optical density, and d4xe2x88x92d3 greater than d3xe2x88x92d2xe2x89xa7d2d1xe2x89xa7d1 is satisfied when each optical density of ink represents each of d1, d2, d3 and d4 (d1 less than d2 less than d3 less than d4).
(Structure 46) The ink jet recording method according to either one of Structures 40-42, wherein aforesaid ink represents three types of ink each having different optical density of ink, and d3xe2x88x92d2 greater than d2xe2x88x92d1xe2x89xa7d1 is satisfied when each optical density of ink represents each of d1, d2 and d3 (d1 less than d2 less than d3).
(Structure 47) The ink jet recording method according to either one of Structures 39-46, wherein optical density of aforesaid ink satisfies the following relational expression;
dn=dnxe2x88x921xc2x7r(r less than 1)
wherein, dn is optical density of each ink under the condition of dn less than dn+1.
(Structure 48) The ink jet recording method according to Structures 47, wherein the expression of r=xc2xd holds.
(Structure 49) An ink jet recording method to record on a recording medium by jetting ink, wherein when N represents the recording density gradation number to be expressed, N is equal to and greater than 81, and minimum recording density a is not less than (fourth power root of N)xc3x9780 dpi.
(Structure 50) The ink jet recording method according to either one of Structures 40-42, wherein N is in a range from 256 to 16384.
(Structure 50xe2x80x2) The ink jet recording method according to Structures 50, wherein N is in a range from 1024 to 16384.
(Structure 50xe2x80x3) The ink jet recording method according to Structures 50xe2x80x2, wherein N is in a range from 4096 to 16384.
(Structure 51) The ink jet recording method according to either one of Structures 39-50, wherein a monochromatic image is recorded on the recording medium stated above.
(Structure 52) The ink jet recording method according to Structure 40, wherein aforesaid n is in a range from cubic root of N to (fourth power root of N)xc3x973.
(Structure 53) The ink jet recording method according to either one of Structures 39-52, wherein the number of density gradation is square root of N/2 or more per minimum recording unit.
(Structure 54) The ink jet recording method according to either one of Structures 39-53, wherein the number of density gradation per minimum recording unit is L (Lxe2x89xa6N/2), and the recording density gradation number mentioned above is expressed through an error diffusion method.
(Structure 55) The ink jet recording method according to either one of Structures 39-54, wherein the number of density gradation per minimum recording unit is L (Lxe2x89xa6N/2), and a super pixel containing plural sub-pixels each representing the minimum recording unit is defined, and the aforesaid recording density gradation number is expressed for each super pixel.
(Structure 56) The ink jet recording method according to either one of Structures 39-55, wherein M density gradation (Mxe2x89xa6N/2) is expressed by super pixel unit, and an error diffusion method is further used to express the density gradation number.
(Structure 57) The ink jet recording method according to Structures 55 and 56, wherein the super pixel is composed of six or more sub-pixels.
(Structure 58) The ink jet recording method according to either one of Structures 55-57, wherein the super pixel is composed of nine or more sub-pixels.
(Structure 59) The ink jet recording method according to either one of Structures 55-58, wherein one side of the super pixel is 110 xcexcm or less in length.
(Structure 60) An ink jet recording method to record images by jetting ink based on image signals, wherein plural types of ink each having different optical density are used as the aforesaid ink, and in a density gradation curve showing the relationship between a density gradation level reproducible with the minimum recording unit and optical density D of an image formed in accordance with each density gradation level, the expression xcex21xe2x89xa6xcex22 holds when xcex21 represents an inclination of a straight line connecting two points on the density gradation curve corresponding respectively to density gradation levels N1 and N2 and xcex22 represents an inclination of a straight line connecting two points on the density gradation curve corresponding respectively to density gradation levels N3 and N4.
In the foregoing, N1 less than N2 less than N3 less than N4 is an assumption for the density gradation level.
(Structure 61) The ink jet recording method according to Structure 60, wherein optical density of the ink satisfies the following relational expression;
dnxe2x88x92dnxe2x88x921 greater than dnxe2x88x921 greater than dnxe2x88x922xe2x89xa7 . . . xe2x89xa7d2xe2x88x92d1 (n represents integers of 4 and over)
wherein, dn is optical density of each ink under the condition of dn less than dn+1.
(Structure 62) The ink jet recording method according to either one of Structures 60 and 61, wherein optical density of the ink satisfies the following relational expression.
dnxe2x88x92dnxe2x88x921 greater than dnxe2x88x921 greater than dnxe2x88x922xe2x89xa7 . . . xe2x89xa7d2xe2x88x92d1xe2x89xa7d1 (n represents integers of 4 and over)
(Structure 63) The ink jet recording method according to either one of Structures 60-62, wherein the aforesaid ink includes four types of ink each having different optical density, and the expression of d4xe2x88x92d3 greater than d3xe2x88x92d2xe2x89xa7d2xe2x88x92d1d1xe2x89xa7d1 holds when each optical density of the ink is represented by each of d1, d2, d3, d4 (d1 less than d2 less than d3 less than d4).
(Structure 64) The ink jet recording method according to Structure 60, wherein the expression of d3xe2x88x92d2xe2x89xa7d2xe2x88x92d1xe2x89xa7d1 holds when each optical density of the ink is represented by each of d1, d2, and d3 (d1 less than d2 less than d3).
(Structure 65) The ink jet recording method according to either one of Structures 60-64, wherein optical density of the ink satisfies the following relational expression;
dn=dnxe2x88x921xc2x7r(r less than 1)
wherein di represents optical density of each ink, and it is assumed to be dn less than dn+1.
(Structure 66) The ink jet recording method according to Structure 65, wherein the expression of r=xc2xd holds.